Process for the manufacture of cement



y 'r. RIGBY PROCESS FOR THE MANUFACTURE OF CEMENT Original FiledJuly-20, 1925 Patented May 10,1927.

UNITED STATES THOMAS BIGBY, OF LONDON, ENGLAND.

PROCESS FOR THE MANUFACTURE OF CEMENT.

Original application filed July 20, 1925, Serial N'o. 44,865, and. inGreat Britain July 28, 1924. Divided 'and this application filedNovember 28, 1925. Serial No. 71,923.

This application is a division of application 44,865 filed July 20,1925.

This invention is concerned with cementmaking by the wet method inrotary kilns by atomizing or similarly dispersing the cement slurry in afinely divided condition in the gases in the kiln so that these lattershall exert a drying action upon and be somewhat cooled by the slurrybefore it is collected on the internal wall of the kiln.

I have found in practice that when sup plying slurry to a kiln in anatomized (ondition it is Well'to take account of the substantialcapacity which the gases may in some cases have to carry dispersedslurry in suspension in them out. ofthe kiln especially where thedispersal is caused to occur only just inside the mouth of the kiln orwhere the kiln is being forced to a high output. Again regard may" withadvantage be paid in some cases to the possibility of utilizing theresidual heat of the gases leaving the kiln for although unusual coolingof the gases is to be expected by dispersing the slurry in the kilngases in the kiln yet the recovery of suspended matter from the gasesand of the residual heat of the gases (whether large or small) is apt tobe a matter of substantial economic advantage.

Important features of the invention con- (ern themselves with theseconditions where they present themselves in making cement by atomizingor similarly dispersing slurry into the rotary kiln. p

In accordance with oneof these features space afforded by the kiln headitself is utilized to bring the gases therein into contact with slurrythat'receives cement material carried out of the. kiln by the gases andacts as a convenient vehicle for its removal from out of the gaspassages. J

The above and other features of the invention will become fully evidentto those skilled in the'art from the following description withreference to the accompanying drawing of one form of cement making plantand method illustrative of the invention.

The accompanying drawing shows in sec- 7 tional side elevation thegeneral arrangement of one form of installation forcarrying out aprocess according to the invention.

The upper end of the kiln is shown at 3 opening intothe kiln headthrough the rear wall 5 of which slurry sprayi nozzles 7 and 8areshown-as operating. T ese project the spray into the kiln through thegas space 9 of the kiln head.

It may happen, especially when the kiln is forced and an unduly highrate of output is sought after, that there arises a tendency for partlydried material to be carried out of the kiln by the gases. This may tendto block up the smoke chamber in the kiln in time if not attended toespecially as such material may in a-partly dried and sticky conditionsettle in this chamber and be difficult to remove apart from theinconveniente involved in providing for this purpose opportunities ofaccess to this chamber.

Such inconveniences may be overcome by providing for the gases meeting aliquid inv this smoke chamber in which suspended material is deposited.For; example, the base of the smoke chamber may have in it or act as acontainer for water or slurry and if such container be equipped withmeans for agitating the liquid the deposited matter is easily stirredmore or less homogeneously into the contents of the container andwithdrawn readily with the liquid.

In the drawing the kiln head is shown as converted into a reservoir forslurry over which the gases from the kiln are caused to ass in flowingdown between the rear wall 5 of the head and the front wall 35 ofthe'latter and up behind the wall 5 and over the wall 37 away to thechimney, this slurry (which is fed in through an inlet 33) being keptstirred by compressed air from pipes indicated at 39 and withdrawn froma well 41 outside the kiln head and into which. well the slurry passesthrough an opening 43 beand well.

Where in a case as referred to slurry for the spraying nozzles 7, 8, ofthe kilnis used as the liquid to catch the deposits this obviouslybecomes advantageously concentrated before being passed to the kiln bythe matter deposited in it. If water or weak slurry is used and it doesnot by the admixture with it of deposited matter reach a condition whichfits it forsupply, if desired, to the kiln it may be used in the slurrymaking installation of the plant so thatits contents of cement materialsshall not be wasted. Such an exposure of the gases to a liquid inpassing from the kiln to the chimneywill low the levels of the liquid inthe reservoir in use in cement plants but even if it does not in thisway avoid losses of cement materials that are inevitable'to-day it willat all events facilitate dealing with what is caught from the gasessince the dry dust usually caught is troublesome to collect andtransport to where it can be made use of.

' The exposure of the gases to a liquid in the kiln head as describedwill inevitablybe accompanied by some cooling of the gases andevaporation of water which in the case viding the kiln head instead oforin addition to a container for liquid ashas been above mentioned, withsuitable slurry atom-.

izing or like dispersing means such for example as one or more slurryspraying nozzles directing a spray or sprays down the kiln head from,and it may be through, one or more openings in the kiln head at or nearits top.

In any case such as described where the gases from the kiln arecleansedor cooled y (or material carried out of the kiln by the gases iscaught in liquid such for instance as slurry the liquid may, either bepassed through the gas contact space and forthwith utilized as desiredor it may be continuously withdrawn from the said space and returned toit anew, only a portion of the circulating liquid being continuously orfrom time to time withdrawn for use as desired and this loss made goodby the addition of fresh liquid to the circulating bulk. Any slurryenriched from the gases by material carried out of the kiln'therebyshould be very thoroughly mixed before being passed to the sprayingdevices of the kiln and accordingly it may be desirable after any suchslurry is withdrawn from thedevice in which it is exposed to thegases-from vices.

liquid container will be arranged entirely and it may in some cases beadvantageous to arrange that the container for liquid which. collectsthe material carried out of "the kiln by the gases is partly in the kilnhead and partly-outside the head-to facilitate provision of stirring andmixing -de- It may be in some cases that the outside the kiln head inwhich case arran ement will preferably be made by suita le conveyingmeans such as a travelling band or bands for example in the floor of thekiln head to take deposited material from the kiln head into the liquidcontainer'which liquid then becomes a vehicle for the'expeditiousremoval of the deposited material.

Such an arrangement would be advantaw, geous in cases where extensivemixing or grinding is required asoopen inspection of the mixture is thusfacilitated and usually the container will be arranged as nearlyadjacent to the kiln head as is possible.

What I claim as my invention and desire to secure by Letters Patent isIn a wet process of making cement in a heated rotary kiln having a headat the gas exit end thereof and a chamber immediately beneath and incommunication with said gas exit end, the step of immediately passingthe hot "gases, carrying solid particles from the kiln, upon their exittherefrom, over a body of slurry in said chamber, whereby theheaviestparticles of any material swept out of .the kiln fall-by gravity and areentrained by the slurry in sai chamber in the kiln head.

In test'mony whereof I aflix my signature.

. THOMAS RIGBY.

